SummaryThe scientific motivation of this project is the significant presence of organic compounds at the surface of the ocean. They form the link between ocean biogeochemistry through the physico-chemical processes near the water-air interface with primary and secondary aerosol formation and evolution in the air aloft and finally to the climate impact of marine boundary layer aerosols. However, their photochemistry and photosensitizer properties have only been suggested and discussed but never fully addressed because they were beyond reach. This project suggests going significantly beyond this matter of fact by a combination of innovative tools and the development of new ideas.
This project is therefore devoted to new laboratory investigations of processes occurring at the air sea interface to predict emission, formation and evolution of halogenated radicals and aerosols from this vast interface between oceans and atmosphere. It progresses from fundamental laboratory measurements, marine science, surface chemistry, photochemistry … and is therefore interdisciplinary in nature.
It will lead to the development of innovative techniques for characterising chemical processing at the air sea interface (e.g., a multiphase atmospheric simulation chamber, a time-resolved fluorescence technique for characterising chemical processing at the air-sea interface). It will allow the assessment of new emerging ideas such as a quantitative description of the importance of photosensitized reactions in the visible at the air/sea interface as a major source of halogenated radicals and aerosols in the marine environment.
This new understanding will impact on our ability to describe atmospheric chemistry in the marine environment which has strong impact on the urban air quality of coastal regions (which by the way represent highly populated regions ) but also on climate change by providing new input for global climate models.

The scientific motivation of this project is the significant presence of organic compounds at the surface of the ocean. They form the link between ocean biogeochemistry through the physico-chemical processes near the water-air interface with primary and secondary aerosol formation and evolution in the air aloft and finally to the climate impact of marine boundary layer aerosols. However, their photochemistry and photosensitizer properties have only been suggested and discussed but never fully addressed because they were beyond reach. This project suggests going significantly beyond this matter of fact by a combination of innovative tools and the development of new ideas.
This project is therefore devoted to new laboratory investigations of processes occurring at the air sea interface to predict emission, formation and evolution of halogenated radicals and aerosols from this vast interface between oceans and atmosphere. It progresses from fundamental laboratory measurements, marine science, surface chemistry, photochemistry … and is therefore interdisciplinary in nature.
It will lead to the development of innovative techniques for characterising chemical processing at the air sea interface (e.g., a multiphase atmospheric simulation chamber, a time-resolved fluorescence technique for characterising chemical processing at the air-sea interface). It will allow the assessment of new emerging ideas such as a quantitative description of the importance of photosensitized reactions in the visible at the air/sea interface as a major source of halogenated radicals and aerosols in the marine environment.
This new understanding will impact on our ability to describe atmospheric chemistry in the marine environment which has strong impact on the urban air quality of coastal regions (which by the way represent highly populated regions ) but also on climate change by providing new input for global climate models.

SummaryMelting in the Earth’s mantle rules the deep volatile cycles because it produces liquids that concentrate and redistribute volatile species. Such redistributions trigger volcanic degassing, magma emplacement in the crust and hydrothermal circulation, and other sorts of chemical redistribution within the mantle (metasomatism). Melting also affects mantle viscosities and therefore impacts on global geodynamics. So far, experimental petrology has been the main approach to construct a picture of the mantle structure and identify regions of partial melting.
Magnetotelluric (MT) surveys reveal the electrical properties of the deep Earth and show highly conductive regions within the mantle, most likely related to volatiles and melts. However, melting zones disclosed by electrical conductivity do not always corroborate usual pictures deduced from experimental petrology. In 2008, I proposed that small amount of melts, very rich in volatiles species and with unusual physical properties, could reconcile petrological and geophysical observations. The broadening of this idea is however limited by (i) the incomplete knowledge of both petrological and electrical properties of those melts and (ii) the lack of petrologically based models to fit MT data. ELECTROLITH will fill this gap by treating the following points:
- How volatiles in the H-C-S-Cl-F system trigger the beginning of melting and how it affects mantle conductivity?
- What are the atomic structures and the physical properties of such volatile-rich melts?
- How can such melts migrate in the mantle and what are the relationships with deformation?
- What are the scaling procedures to integrate lab-scale observations into a petrological scheme that could decipher MT data in terms of melt percolation models, strain distributions and chemical redistributions in the mantle
ELECTROLITH milestone is therefore a reconciled perspective of geophysics and petrology that will profoundly enrich our vision of the mantle geodynamics

Melting in the Earth’s mantle rules the deep volatile cycles because it produces liquids that concentrate and redistribute volatile species. Such redistributions trigger volcanic degassing, magma emplacement in the crust and hydrothermal circulation, and other sorts of chemical redistribution within the mantle (metasomatism). Melting also affects mantle viscosities and therefore impacts on global geodynamics. So far, experimental petrology has been the main approach to construct a picture of the mantle structure and identify regions of partial melting.
Magnetotelluric (MT) surveys reveal the electrical properties of the deep Earth and show highly conductive regions within the mantle, most likely related to volatiles and melts. However, melting zones disclosed by electrical conductivity do not always corroborate usual pictures deduced from experimental petrology. In 2008, I proposed that small amount of melts, very rich in volatiles species and with unusual physical properties, could reconcile petrological and geophysical observations. The broadening of this idea is however limited by (i) the incomplete knowledge of both petrological and electrical properties of those melts and (ii) the lack of petrologically based models to fit MT data. ELECTROLITH will fill this gap by treating the following points:
- How volatiles in the H-C-S-Cl-F system trigger the beginning of melting and how it affects mantle conductivity?
- What are the atomic structures and the physical properties of such volatile-rich melts?
- How can such melts migrate in the mantle and what are the relationships with deformation?
- What are the scaling procedures to integrate lab-scale observations into a petrological scheme that could decipher MT data in terms of melt percolation models, strain distributions and chemical redistributions in the mantle
ELECTROLITH milestone is therefore a reconciled perspective of geophysics and petrology that will profoundly enrich our vision of the mantle geodynamics

SummaryICE&LASERS propose to make a breakthrough in two challenges of paleoclimate science:
(1) Extending the Antarctic ice core records to 1.5 million years ago is critical to understand the unexplained climate shift from 40,000-year periodicities to 100,000-year ones, calling for a different climate sensitivity to orbital forcing. We propose to revolutionize ice core science by building an innovative probe making its own way into the ice sheet within a single field season, to measure in situ the depth profile of H2O isotopes in ice as well as greenhouse gas concentration in trapped gases, down to bedrock. This high gain/high risk project will allow us to rapidly qualify different “oldest ice” sites, and to immediately obtain the main climatic signals of interest;
(2) Why the atmospheric CO2 and CH4 concentrations varied by up to 40 and 100%, respectively, during glacial-interglacial cycles is still highly debated. We will combine revolutionary detectors with new extraction techniques to measure with unsurpassed accuracy and resolution the concentrations of CH4, CO2 and CO (a tracer related to the CH4 cycle), and the isotopic ratios of CO2 and CO in polar ice. We will constrain theories of past changes in the carbon cycle and of climate feedbacks, and will provide more insight into possible natural feedbacks under a warming future.
ICE&LASERS tackles both scientific challenges, thanks to an analytical revolution for measuring trace gases and their stable isotopes: Optical-Feedback Cavity-Enhanced Absorption Spectroscopy (OFCEAS), recently patented by one of the four CNRS research units involved in the project. ICE&LASERS will contribute to maintain European ice core science at its current leading position, and to optimize the transfer of innovative laser physics to important environmental problems.

ICE&LASERS propose to make a breakthrough in two challenges of paleoclimate science:
(1) Extending the Antarctic ice core records to 1.5 million years ago is critical to understand the unexplained climate shift from 40,000-year periodicities to 100,000-year ones, calling for a different climate sensitivity to orbital forcing. We propose to revolutionize ice core science by building an innovative probe making its own way into the ice sheet within a single field season, to measure in situ the depth profile of H2O isotopes in ice as well as greenhouse gas concentration in trapped gases, down to bedrock. This high gain/high risk project will allow us to rapidly qualify different “oldest ice” sites, and to immediately obtain the main climatic signals of interest;
(2) Why the atmospheric CO2 and CH4 concentrations varied by up to 40 and 100%, respectively, during glacial-interglacial cycles is still highly debated. We will combine revolutionary detectors with new extraction techniques to measure with unsurpassed accuracy and resolution the concentrations of CH4, CO2 and CO (a tracer related to the CH4 cycle), and the isotopic ratios of CO2 and CO in polar ice. We will constrain theories of past changes in the carbon cycle and of climate feedbacks, and will provide more insight into possible natural feedbacks under a warming future.
ICE&LASERS tackles both scientific challenges, thanks to an analytical revolution for measuring trace gases and their stable isotopes: Optical-Feedback Cavity-Enhanced Absorption Spectroscopy (OFCEAS), recently patented by one of the four CNRS research units involved in the project. ICE&LASERS will contribute to maintain European ice core science at its current leading position, and to optimize the transfer of innovative laser physics to important environmental problems.

Max ERC Funding

2 986 718 €

Duration

Start date: 2012-03-01, End date: 2018-02-28

Project acronymPALEONANOLIFE

ProjectResponses of precambrian life to environmental changes

Researcher (PI)François Michel Raoul Robert

Host Institution (HI)MUSEUM NATIONAL D'HISTOIRE NATURELLE

Call DetailsAdvanced Grant (AdG), PE10, ERC-2011-ADG_20110209

SummaryThis multidisciplinary proposal has the objective to enhance our knowledge on the early steps of the evolution of life on Earth by providing a foundation for better deciphering the molecular fossil record as well as the geochemical signals hidden in ancient rocks. Based on the multiscale and multitechnique study of morphologically preserved microorganisms fossilized within ancient siliceous nodules, I propose to chronologically reconcile the evolution of metabolisms of life forms during the Precambrian with the variation of (sea)water paleo-temperatures registered by the silica matrix in which the investigated organic microfossils are embedded.
Spatially-resolved information on fossil organic constituent speciation and their structural relationships with the silica matrix will be obtained at the nanometer scale using a unique combination of spectroscopy and microscopy techniques, notably including STXM and TEM. Crucial information on paleo-metabolisms will be obtained from NanoSIMS experiments by measuring the stable H-C-N-S isotope composition of the investigated fossilized objects at the scale of individual cells. In parallel, laboratory experiments will be conducted to better assess the potential isotopic and molecular evolution of organic molecules during the fossilization process. Estimations of water paleo-temperatures – likely corresponding to oceanic paleo-temperatures – will be achieved based on the distribution of the silicon and oxygen isotopic composition of silica closely associated to the fossil cells, measured at the very high spatial resolution of the NanoSIMS. Furthermore, the study of natural proxies will provide a more profound understanding of the significance of the temperature registered by the isotopic compositions of Precambrian cherts. In addition to radically change scientific ideas about Precambrian Paleontology, the technical and scientific developments resulting from this work will be broadly applicable and serve numerous communities.

This multidisciplinary proposal has the objective to enhance our knowledge on the early steps of the evolution of life on Earth by providing a foundation for better deciphering the molecular fossil record as well as the geochemical signals hidden in ancient rocks. Based on the multiscale and multitechnique study of morphologically preserved microorganisms fossilized within ancient siliceous nodules, I propose to chronologically reconcile the evolution of metabolisms of life forms during the Precambrian with the variation of (sea)water paleo-temperatures registered by the silica matrix in which the investigated organic microfossils are embedded.
Spatially-resolved information on fossil organic constituent speciation and their structural relationships with the silica matrix will be obtained at the nanometer scale using a unique combination of spectroscopy and microscopy techniques, notably including STXM and TEM. Crucial information on paleo-metabolisms will be obtained from NanoSIMS experiments by measuring the stable H-C-N-S isotope composition of the investigated fossilized objects at the scale of individual cells. In parallel, laboratory experiments will be conducted to better assess the potential isotopic and molecular evolution of organic molecules during the fossilization process. Estimations of water paleo-temperatures – likely corresponding to oceanic paleo-temperatures – will be achieved based on the distribution of the silicon and oxygen isotopic composition of silica closely associated to the fossil cells, measured at the very high spatial resolution of the NanoSIMS. Furthermore, the study of natural proxies will provide a more profound understanding of the significance of the temperature registered by the isotopic compositions of Precambrian cherts. In addition to radically change scientific ideas about Precambrian Paleontology, the technical and scientific developments resulting from this work will be broadly applicable and serve numerous communities.

Max ERC Funding

1 468 852 €

Duration

Start date: 2012-07-01, End date: 2017-12-31

Project acronymRHEOLITH

ProjectRheology of the continental lithosphere, a geological, experimental and numerical approach

Researcher (PI)Laurent Jolivet

Host Institution (HI)UNIVERSITE D'ORLEANS

Call DetailsAdvanced Grant (AdG), PE10, ERC-2011-ADG_20110209

SummaryA better comprehension of the rheology of the lithosphere is required to relate long and short term deformation regimes and describe the succession of events leading to earthquakes. But our vision of the rheology is blurred because gaps exist between visions of geologists, experimentalists and modellers. Geologists describe the evolution of a structure at regional-scale within geological durations. Specialists of experimental rheology control most parameters, but laboratory time constants are short and they often work on simple synthetic rocks. Specialists of modelling can choose any time- and space-scales and introduce in the model any parameter, but the resolution of their models is low compared to natural observations, and mixing short-term and long-term processes is uneasy. It seems now clear that there is not one rheological model applicable to all contexts and that rheological parameters should be adapted to each situation. We will work on exhumed crustal-scale shear zones and describe them in their complexity, focussing on strain localisation and high strain structures that can lead to fast slip events. A number of objects will be studied, starting from geological description (3D geometry, P-T-fluids estimates and dating), experimental studies of rheological properties of natural sampled rocks and numerical modelling. We will set an Argon-dating lab to work on dense sampling for dating along strain gradients in order to overcome local artefacts and quantify rates of strain localisation. We will deform in the lab natural rocks taken from the studied objects to retrieve adapted rheological parameters. We will model processes at various scales, from the lab to the lithosphere in order to ensure a clean transfer of rheological parameters from one scale to another.

A better comprehension of the rheology of the lithosphere is required to relate long and short term deformation regimes and describe the succession of events leading to earthquakes. But our vision of the rheology is blurred because gaps exist between visions of geologists, experimentalists and modellers. Geologists describe the evolution of a structure at regional-scale within geological durations. Specialists of experimental rheology control most parameters, but laboratory time constants are short and they often work on simple synthetic rocks. Specialists of modelling can choose any time- and space-scales and introduce in the model any parameter, but the resolution of their models is low compared to natural observations, and mixing short-term and long-term processes is uneasy. It seems now clear that there is not one rheological model applicable to all contexts and that rheological parameters should be adapted to each situation. We will work on exhumed crustal-scale shear zones and describe them in their complexity, focussing on strain localisation and high strain structures that can lead to fast slip events. A number of objects will be studied, starting from geological description (3D geometry, P-T-fluids estimates and dating), experimental studies of rheological properties of natural sampled rocks and numerical modelling. We will set an Argon-dating lab to work on dense sampling for dating along strain gradients in order to overcome local artefacts and quantify rates of strain localisation. We will deform in the lab natural rocks taken from the studied objects to retrieve adapted rheological parameters. We will model processes at various scales, from the lab to the lithosphere in order to ensure a clean transfer of rheological parameters from one scale to another.

SummaryUnderstanding mantle convection is essential to understand the thermal and chemical evolution of the Earth and to constrain the forces driving plate tectonics. The rheological properties of the mantle are traditionally inverted from surface geophysical data. Radial profiles of the viscosity are thus available but a lot of uncertainties remain.
A more detailed model of mantle rheology could be obtained from the knowledge of the constitutive flow laws of mantle phases. A lot of progresses have been achieved to extend the P, T range accessible to rheological studies. However, constitutive flow laws are only available so far for minerals from the upper mantle. More severe is the timescale issue since phenomenological flow laws must be extrapolated over several orders of magnitude to be applied to mantle convection.
Recently, a new field has emerged in materials science called multiscale modelling. It allows to link our understanding of a few elementary mechanisms (usually at the microscopic scale) with a behaviour observed at the macroscopic scale. I consider that this offers a ground-breaking opportunity to set a microphysics-based model of the rheology of mantle phases. Much progress has recently been obtained by my group in this direction. A multiscale model of plastic flow consist in modeling:
a) the defects responsible for plastic shear at the atomic scale (dislocations);
b) their mobility under the influence of stress and temperature;
c) their collective behaviour resulting in plastic flow.
I propose to build upon those accomplishments and to model the plastic flow of some key phases of the Earth’s mantle: wadsleyite, ringwoodite, MgSiO3 perovskite and post-perovskite to constrain:
i) the viscosity contrast between the transition zone and the lower mantle;
ii) the viscosity profile of the lower mantle (and understand the origin of the peak of viscosity at mid-mantle);
iii) the rheology at the thermal boundary with the core.

Understanding mantle convection is essential to understand the thermal and chemical evolution of the Earth and to constrain the forces driving plate tectonics. The rheological properties of the mantle are traditionally inverted from surface geophysical data. Radial profiles of the viscosity are thus available but a lot of uncertainties remain.
A more detailed model of mantle rheology could be obtained from the knowledge of the constitutive flow laws of mantle phases. A lot of progresses have been achieved to extend the P, T range accessible to rheological studies. However, constitutive flow laws are only available so far for minerals from the upper mantle. More severe is the timescale issue since phenomenological flow laws must be extrapolated over several orders of magnitude to be applied to mantle convection.
Recently, a new field has emerged in materials science called multiscale modelling. It allows to link our understanding of a few elementary mechanisms (usually at the microscopic scale) with a behaviour observed at the macroscopic scale. I consider that this offers a ground-breaking opportunity to set a microphysics-based model of the rheology of mantle phases. Much progress has recently been obtained by my group in this direction. A multiscale model of plastic flow consist in modeling:
a) the defects responsible for plastic shear at the atomic scale (dislocations);
b) their mobility under the influence of stress and temperature;
c) their collective behaviour resulting in plastic flow.
I propose to build upon those accomplishments and to model the plastic flow of some key phases of the Earth’s mantle: wadsleyite, ringwoodite, MgSiO3 perovskite and post-perovskite to constrain:
i) the viscosity contrast between the transition zone and the lower mantle;
ii) the viscosity profile of the lower mantle (and understand the origin of the peak of viscosity at mid-mantle);
iii) the rheology at the thermal boundary with the core.